Mark faces to use different textures
You can use different material settings in 1 shader and mix them.

Here you have 2 diffuse shaders using different textures. The mix shader uses as factor a random objet info to choose wich one to use. the color ramp, set on constant, allows to use only 1 one them, not a random mix of the 2 (constant) and the Position at 0.5 allows a 50% mix, but you can have more or less of a material moving the slider left or right.